The present invention relates to a paddle support for pipelines. In particular, the invention relates to a paddle support to be mounted on a pig for use in a pipeline.
Various deposits can accumulate on the inner surface of oil and gas pipelines such as rust, wax or dirt. Such deposits are conventionally removed using pigs, which are cylindrical or spherical capsules inserted into the pipeline to move along the pipe. The pigs are often adapted to scrape the inner surface of the pipeline as they travel, though they may be used for many other purposes such as gauging the internal bore of the pipeline or monitoring pipeline condition and integrity.
Known pigs consist of a pig body, seals and fittings. The fittings include brushes and scraper blades, and also support sleeves for centralising the pig within the pipeline. Conventional support sleeves consist of solid discs, although xe2x80x98Vxe2x80x99-shaped notches are often cut out of the circumference of the disc. This is particularly the case for use in pipelines which reduce in diameter, as the notches promote bending deformation of the support sleeve in the longitudinal direction.
The seals are conventionally solid rubber discs used to drive the pig as a pressurised fluid acts upon them. The solid seals tend to produce a large pressure upstream of the pig. By-pass ports within the pig body may be used to reduce this pressure and also provide a jetting action to improve cleaning of the pipeline.
It is often necessary to reduce the diameter of the pipeline. In such cases, dual-diameter pigs are often used. The seals of the pig, sized to match the larger internal pipe diameter must deform to fit the lesser pipe diameter. Conventionally, the seals are available in three types: disc, standard cup and conical cup, with the conical cup seal deforming best. Large forces are required to deform the support sleeve, which tends to have a greater depth than the seals.
It is an object of the present invention to provide a support which centralises a pig within a pipeline while reducing the force that is required to deform the support. It is a further object of the invention to provide a support which may easily deform when reaching a reduction in the internal diameter of the pipeline.
According to a first aspect of the invention there is provided a support sleeve for supporting an internal pipeline apparatus within a pipeline, the sleeve being adapted to be received on the pipeline apparatus and including a plurality of resiliently deformable splines extending radially outwardly from the sleeve, wherein the sleeve has a longitudinal axis and each spline is adapted to resiliently deform in a direction transverse to the longitudinal axis when a force substantially parallel to the longitudinal axis is applied to the spline.
Preferably, each spline deforms in a substantially circumferential direction about the longitudinal axis when the force is applied to the spline. Most preferably, each spline is profiled to promote buckling of the spline in the circumferential direction when the force is applied.
Preferably, each spline has a pair of leading edges, each of the leading edges being chamfered so as to promote buckling of the spline.
Preferably, each spline has a depth and a width, the depth being greater than the width.
Preferably, the splines are integrally formed on the sleeve.
Preferably, the sleeve is manufactured from a polyurethane material.
Preferably, the sleeve is substantially cylindrical and at least one end of the sleeve is open. Preferably, the splines are equidistantly spaced around the circumference of the sleeve.
According to a second aspect of the present invention, there is provided an internal pipeline apparatus comprising a body portion and a support sleeve in accordance with the first aspect of the present invention.
Preferably, the apparatus further comprises at least one annular seal mounted on the body portion.
In a preferred embodiment, the sleeve is fixedly attached to the body portion. Alternatively, the sleeve may be attached to the body portion such that it may rotate relative to the body portion.